This invention pertains to the art of wheelchairs, and more particularly to powered wheelchairs. The invention is particularly applicable to battery powered wheelchairs, and will be described with particular reference thereto. It will be appreciated that the invention has broader applications and may be advantageously employed in related powered wheelchairs and not restricted to the particular embodiment described.
Present day wheelchair manufacturers employ substantially similar drive mechanisms for battery powered wheelchairs. Specifically, suitable connections are made between the battery and first and second drive motors. The drive motors are generally attached to the frame underneath or immediately behind the seat. They are positioned generally parallel to side frames of the wheelchair. That is, output shafts of the drive motors are disposed substantially parallel to the side frames. The driven wheels of the powered wheelchair are oriented for rotation in planes generally parallel to the side frames, i.e., rotation about axes substantially perpendicular to the side frames.
It has been known to mount the drive motors transversely with respect to the side frames. Such an arrangement greatly restricts, however, the ability to collapse the wheelchair.
A primary reason for the "parallel" mounting of the drive motors (i.e. parallel to the side frames) is the development of powered wheelchairs as evolved from motorizing non-powered, collapsible wheelchairs. The non-powered or manual wheelchairs had developed to a stage in which the folded or collapsible nature was heavily emphasized for transport and storage reasons. Adapting drive motors to these wheelchairs generally restricted the drive motors to a parallel mounting arrangement because of the collapsible nature of the wheelchair. The wheelchair manufacturers became accustomed to this original mounting arrangement and generally have continued to construct powered wheelchairs in a parallel mounting arrangement of the drive motors.
It is believed that another reason for this parallel mounting arrangement of the drive motors is aesthetics. That is, the drive motors may be effectively "hidden" by mounting the motors under the seat in a parallel arrangement with the side frames. Also, in limited situations, this arrangement of the drive motors would still permit partial collapsing of the wheelchair to increase the ease of transportation.
However, maximum collapsing of the wheelchair to improve the ease of transportation is not effectively accomplished by the known methods of mounting the drive motors. The typical powered wheelchair carries a battery. A rigid platform extends between the side frames to support the battery. Therefore, to fully collapse the wheelchair the battery and platform would have to be removed from the wheelchair.
Thus, to improve the collapsible nature of the wheelchair and therefore improve the ease with which powered wheelchairs can be transported, it would be desirable to remove the motors from their normal parallel arrangement and remove the batteries and rigid platform which extends between the side frames.
U.S. Pat. No. 3,908,776 to Dudley discloses an attempt to remove the motors from beneath the wheelchair seat area. Two electric motor units 9 are wholly disposed in the interior of the hub 1 of the rear wheels of the wheelchair. The motor units 9 are positioned to respective opposite sides of the axis of rotation of the wheel. Two driving gearwheels 10 which are rotated by the respective motor units 9 are engagable with an annular plate 8. Thus, gears of the stationary motors located within the wheel hub rotate the rear wheels by engaging the annular plate 8. Dudley further discloses that a battery tray and batteries carried thereby are used, but that they have been omitted in the Figures. Thus, even with the wheel hub mounting of the motors, the batteries of Dudley still are located between the wheels, thereby obstructing maximum collapse of the wheelchair.